This invention relates a device for preventing reverse gear buzzing upon reverse shifting operation in a manual transmission or to a synchronizing device for reverse shifting operation.
As reverse shifting operation in a manual transmission is conducted in principle when the vehicle is stopped, gears are designed to be slidingly meshed with each other without provision of a synchronizing device, in general. However, recently a low-viscosity lubricating oil for the manual transmission has been often employed in order to reduce fuel consumption of an engine of the vehicle and improve a speed change operation at low temperatures. As a result, even when the clutch is released, the input shaft in the transmission continues to inertially rotate under no-load conditions, thereby causing poor manipulation upon the reverse shifting operation as well as creating reverse gear buzzing. This noise will make the driver unpleasant, and in the worst case, the gears may be damaged. Such a noise tends to be created especially when the engine idling speed is required to be set to a higher value because of operation of an air-conditioning or cooling device in summer.